Feedback and Feedforward Hybrid Control of Primary Coolant Discharge Temperature with Smith Predictor

The primary coolant discharge temperature control system is an important part of the pressurized water reactor. The component cooling water in the non-regenerative heat exchanger is applied to cool the discharge flow within the permissible temperature. The primary coolant discharge temperature control system is a process with a large time lag. Therefore, to improve the temperature control effect and avoid over-temperature alarms, this study proposes a feedback and feedforward hybrid controller with Smith predictor. The feedback part uses the Smith predictor to compensate the system delay. The object model is identified based by the least square method. The feedforward control considers four measurable disturbances including inlet temperature, charge flow, discharge flow, cooling water flow, to compensate for the impact of these disturbances on the discharge outlet temperature. Based on the mass, energy and momentum conservation equations, a nonlinear dynamic model of primary coolant discharge temperature control system was obtained. The simulation experiments were carried out on the dynamic model. The experiments showed that compared with the traditional controller, the designed controller has the characteristics of smaller overshoot, faster response time, better robustness performance.